Apparatuses and methods for sorting out products are widely known. They may serve to segregate products that are not in conformance with the desired product properties. The term “product” is used in this context as a collective term for articles of all kinds, including in particular products that are already packaged. Especially in the pharmaceutical industry and in the food industry, such sorting methods are used with preference in order to ensure that downstream of the sorting apparatus only those products which conform to the properties desired by the manufacturer remain in the transport line.
Products that lack the specified properties are deflected off the conveyor path and arrive in a collection zone where they can be collected for example in holding bins. To identify the products to be sorted out or deflected, appropriate (negative) sorting criteria are set in accordance with the specified properties. Such sorting criteria can be weight defects (over- or underweight articles), packaging defects, contaminated products and other nonconformances. While traveling down the conveyor path, the products are inspected according to at least one of these sorting criteria. If a product fails under at least one of the given criteria, it will after this inspection be diverted from the conveyor path and separated.
Sorting apparatuses normally operate automatically in conjunction with inspection devices, i.e. devices that perform tests in accordance with a given sorting-out criterion. In other words, the testing in accordance with the given sorting criteria as well as the turning-away of the products to be separated occurs in an automated process, normally under the control of an electronic controller unit.
The state of the art offers a diversity of sorting apparatuses. A method and a device for the sorting of products are described for example in EP 1 798 180 A2, wherein the products are inspected according to at least two given sorting criteria and, in case one of the criteria is satisfied, are automatically deflected transverse to the transport direction towards a receiving area, wherein the deflecting force acts from a common center, independent of which of the criteria has been met and calls for the product to be deflected. Products to be separated are in this case directed to a receiving bin by means of a pusher which moves transverse to the transport direction.
In EP 0 540 148, a device and a method are described for the testing of the leak-tightness as well as for the automated weighing of tightly sealed pouches. Pouches with a defective seal are blown by an air stream into a receiving bin, using a sorter device which is arranged at the side of a conveyor line and supplied with compressed air.
The subject of testing the leak-tightness of sealed pouches is likewise addressed in EP 1 411 337 A1. Products failing the given criterion are transported to a receiving bin by means of a conveyor belt designed to swivel downwards in case of a rejected product.
In the sorting-out of products with the afore-described conventional methods such as using compressed air to direct a product in a desired direction or using a pusher to shove a product out of the conveyor path, a problem is encountered especially in the case of flat and/or light-weight products such as side-sealed pouches, in that the product is either not picked up by the air stream or, because of its light weight, is blown elsewhere instead of to the desired place. When using pushers, one encounters the problem that flat products in particular can jam up with the pusher and can thus, in a worst case, cause the processing line to stop.
Therefore, in order to allow defective products to be sorted out carefully and reliably, the sorting rate in apparatuses of this kind is limited.
If products are to be sorted out by means of a downward-tiltable sorting-out conveyor belt or by means of a downward-pivoting sorting flap, where the segregated products travel along the sorting-out conveyor belt or the sorting flap in order to drop into a receiving bin, the speed of the sorting-out operation is limited by the fact that a direct transfer of the product from the infeed conveyor to the outfeed conveyor, one or both of which could for example be belt conveyors, has to be avoided. In order to reduce the error rate in the sorting-out process, a sufficient amount of time has to be allowed for the product to remain on the downward-tiltable sorting-out conveyor belt or on the sorting flap in order to be reliably transported to the receiving bin.
It would be desirable, therefore, to provide a fast and reliable sorting apparatus which is free of the drawbacks of state-of-the-art devices.